102 GROVE KARL GILBERT— DAVIS [Memoirs [vol™xi; 



true of the first 50 pages of the Henry Mountains report, in which the manifestly consequent 

 radial drainage of certain laccolithic domes is described without any genetic term by which to 

 name it: 



The drainage of Mount Ellsworth is from the center of the dome outward. A half dozen drainage-lines 

 originate in the high crests and pass outward through the zone of upturned strata. Lower down the interspaces 

 are divided by others, and when they reach the circling escarpment of the Vermilion sandstone their number 

 is fifteen (25, 26). 



It might perhaps be inferred from Gilbert's failure to introduce here a systematic termi- 

 nology for stream courses of different kinds, that terminology did not greatly interest him; yet 

 some years later he spoke with much satisfaction of the advantage that had come from his 

 invention of the term "laccolite." Indeed, even for streams, he used a systematic terminology 

 when it came fully to his attention; for in the final chapter on "Land sculpture," Powell's terms, 

 consequent, antecedent, and superimposed are adopted, and it is then concisely said: 



The drainage of the Henry Mountains is consequent on the laccolitic displacements. . . . The drainage 

 system of Mount Ellsworth is more purely consequent than any other with which I am acquainted (144, 145). 



Again, the drainage of the greater arch of Mount Holmes, which still preserves its covering 

 strata, is described as "consequent upon the structure"; that is, on the dip of the up-arched 

 strata; and the successive stages of its development are pleasingly outlined: 



When it was first lifted it became a drainage center because it was an eminence; and afterwards it remained 

 an eminence because it was a drainage center. When in the progress of denudation its dikes were exposed, their 

 hardness checked the wear of the summit and its eminence became more pronounced (147). 



Gilbert's final adoption of "consequent" and its associates of Latin origin in the sense above 

 indicated was evidently the result of conference with Powell, by whom they had been announced 

 two years before in his Colorado River report. It is of interest to note in this connection that, 

 of the two sets of terms which Powell introduced, one of Greek derivation, embodying an empi- 

 rical relation of streams to structures, and the other of Latin derivation, indicating a genetic 

 relation of streams to structures, Gilbert, familiar with both, preferred the latter. His famil- 

 iarity with the first set is shown in a notebook entry of September 20, 1876, a year after the Colo- 

 rado River report was published. During an ascent of one of the laccolithic mountains on that 

 date it was recorded that the horses were left at a certain point, beyond which the party " trav- 

 eled all the way cataclinal, the dip being 7° by guess & our course inclining 20°"; but excepting 

 "monoclinal," the other terms of this set were not elsewhere employed. As to the terms of the 

 other set, they appear to have been familiar at least a year earlier, for a note under date of 

 July 12, 1875, uses both " antecedent" and " superimposed." In view of this it is surprising that 

 " consequent" was used the same year in a sense altogether different from that which Powell had 

 given to it, as the following narrative account will show. 



THE WATERPOCKET CANTON 



It will be remembered that Gilbert first approached the Henry Mountains in the summer 

 of 1875 from the west, and that on the way he crossed the greatly degraded east-dipping mono- 

 cline of the long Waterpocket flexure, which trends about north and south. In the northern 

 part of its length the flexure is traversed by the east-flowing headwaters of Dirty Devil River, 

 which in its farther course flows around the mountains on the north and east to the Colorado; 

 but the southernmost 30 miles of the flexure are followed by a continuous longitudinal valley, 

 excavated along a belt of weak shales between the rising roll of underlying sandstones on the 

 west and the escarpment of overlying sandstones on the east. This valley which Gilbert 

 describes in his report as the longest monoclinal drainage line with which he is acquainted — 



here bears the name of Waterpocket cafion . . . The upper part of the canon is dry except in time of rain, but the 

 lower carries a perpetual stream known as Hoxie Creek [which flows directly to the Colorado]. Whatever may 

 have been the original meanderings of the latter they are now restrained, and it is limited to the narrow belt in 

 which the shale outcrops. As the cafion is worn deeper the channel steadily shifts its position down the slope of 

 the underlying . . . sandstone, and carves away the shale. But there is one exceptional point where it has not 



